Implement Fog of War

Build fog of war as a shared perception system with a restrained presentation layer.

Preserve the architecture

Keep these responsibilities separate:

1. Let deterministic CPU perception own ranges, obstacle intersections, and gameplay visibility.
2. Encode the player's angular visible distances into one fixed-size lookup texture.
3. Let one full-screen shader turn that lookup into soft radial and wall-aware fog.
4. Let gameplay consume perception results directly; never infer combat truth from fog pixels.

Read mechanics.md before implementing or changing the algorithm. It records the proven obstacle model, shader composition, calibrated values, state rules, enemy behavior, lighting constraints, and telemetry.

Inspect before editing

• Locate the authoritative player position, camera, obstacles, scene lifecycle, frame loop, targeting, enemy perception, and render layers.
• Confirm the gameplay ground model. The proven corner-unprojection method assumes a locally horizontal plane; use authoritative surface or terrain reconstruction when elevation varies across the visible area.
• Find existing scene fog, post-processing, renderer creation, review modes, menus, captures, transitions, and disposal paths.
• Read the current tests and recent fog/perception commits before changing constants or ownership.
• Confirm whether obstacle state changes at runtime. Reuse the same active obstacle collection used by navigation or collision when its geometry is suitable for sight.
• Check the working tree early and preserve unrelated changes.

Implement in dependency order

1. Define perception truth